Integrated process for carbon capture and energy production

Abstract

The present invention pertains to new methods for generating energy and useful nitrogen compounds from captured carbon dioxide. It involves employing an osmotic engine, draw solution, and feed solution. An osmotic gradient between the solutions assists in generating energy and a solution of ammonium carbonate, ammonium bicarbonate or mixture thereof. This solution may be decomposed to form ammonia, carbon dioxide, a precipitate, or a mixture thereof.

What is claimed is: 
     
       1. A process for separating carbon dioxide comprising:
 forming a first solution comprising a salt of carbonate, bicarbonate, carbamate, or a mixture thereof; and 
 decomposing the first solution to form a second aqueous solution comprising ammonia, amine, carbon dioxide, or a mixture thereof; 
 wherein the decomposing of the first solution to form said second aqueous solution is conducted in the presence of a water-soluble organic solvent to form gaseous carbon dioxide in the absence of precipitate; and then 
 separating at least a portion of the solvent from the second aqueous solution. 
 
     
     
       2. The process of  claim 1  wherein the first and second solution each comprise aqueous ammonia, amine, or both. 
     
     
       3. The process of  claim 1  wherein the decomposing of the first solution occurs in the absence of high pressure. 
     
     
       4. The process of  claim 1  wherein the decomposing of the first solution further uses a pump, vacuum pump, or other device. 
     
     
       5. The process of  claim 1  which further comprises compressing the formed gaseous carbon dioxide. 
     
     
       6. The process of  claim 1  which further comprises bubbling the formed gaseous carbon dioxide through water to remove soluble vapor. 
     
     
       7. The process of  claim 1  which further comprises bubbling the formed gaseous carbon dioxide through water to remove organic solvent vapor, ammonia gas, or both. 
     
     
       8. The process of  claim 1  which further comprises removing organic solvent vapor from the formed gaseous carbon dioxide. 
     
     
       9. The process of  claim 1  which comprises first capturing carbon dioxide from a gas stream to produce the first solution and wherein said gas stream comprises flue gas. 
     
     
       10. The process of  claim 1  which comprises first capturing carbon dioxide from a gas stream to produce the first solution and wherein said gas stream comprises a steam methane reforming gas. 
     
     
       11. The process of  claim 1  which comprises first capturing carbon dioxide from a gas stream to produce the first solution and wherein said gas stream comprises a low temperature gas shift gas. 
     
     
       12. The process of  claim 1  which comprises first capturing carbon dioxide from a gas stream to produce the first solution and wherein said capturing is conducted at a temperature such that a substantial portion of the ammonia is condensed. 
     
     
       13. The process of  claim 1  which comprises first capturing carbon dioxide from a gas stream to produce the first solution and wherein said capturing is conducted at a reduced temperature using a heat sink. 
     
     
       14. The process of  claim 13  wherein the heat sink comprises water. 
     
     
       15. The process of  claim 1  which comprises first capturing carbon dioxide from a gas stream to produce the first solution and wherein said capturing is conducted at a reduced temperature using an absorption column. 
     
     
       16. The process of  claim 1  which comprises first capturing carbon dioxide from a gas stream to produce the first solution and wherein said capturing is conducted at a reduced temperature using an absorption column with a heat sink. 
     
     
       17. The process of  claim 16  wherein the heat sink comprises water. 
     
     
       18. The process of  claim 1  which comprises first capturing carbon dioxide from a gas stream to produce the first solution and wherein said gas stream is subjected to a purification step subsequent to said capturing of carbon dioxide. 
     
     
       19. The process of  claim 18  wherein said purification step captures additional carbon dioxide. 
     
     
       20. The process of  claim 1  wherein the decomposing of the solution occurs at a temperature less than 80° C.